U.S. patent application number 14/837388 was filed with the patent office on 2016-03-03 for ink composition and ink set.
The applicant listed for this patent is Seiko Epson Corporation. Invention is credited to Shiki KUMAGAI, Yusuke MIZUTAKI, Tomoyuki OKUYAMA, Tsuyoshi SANO.
Application Number | 20160060473 14/837388 |
Document ID | / |
Family ID | 54012102 |
Filed Date | 2016-03-03 |
United States Patent
Application |
20160060473 |
Kind Code |
A1 |
SANO; Tsuyoshi ; et
al. |
March 3, 2016 |
INK COMPOSITION AND INK SET
Abstract
There is provided an ink composition including: a pigment; a
polymer dispersant; water; and a water-soluble organic solvent, in
which the pigment includes Pigment Yellow 74, and the integrated
value of absorbance of light having a wavelength of 300 nm to 400
nm is 30% or less with respect to 100% of the integrated value of
absorbance of light having a wavelength of 300 nm to 600 nm.
Inventors: |
SANO; Tsuyoshi; (Shiojiri,
JP) ; OKUYAMA; Tomoyuki; (Chino, JP) ;
MIZUTAKI; Yusuke; (Shiojiri, JP) ; KUMAGAI;
Shiki; (Shiojiri, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Seiko Epson Corporation |
Tokyo |
|
JP |
|
|
Family ID: |
54012102 |
Appl. No.: |
14/837388 |
Filed: |
August 27, 2015 |
Current U.S.
Class: |
524/88 ;
524/190 |
Current CPC
Class: |
C09D 153/00 20130101;
C09D 11/36 20130101; C09D 11/106 20130101; C09D 11/40 20130101;
C08K 5/3437 20130101; C09D 11/322 20130101; C09D 151/003 20130101;
C08K 5/3417 20130101; C08K 5/23 20130101 |
International
Class: |
C09D 11/40 20060101
C09D011/40; C08K 5/3417 20060101 C08K005/3417; C08K 5/3437 20060101
C08K005/3437; C09D 151/00 20060101 C09D151/00; C08K 5/23 20060101
C08K005/23; C09D 11/36 20060101 C09D011/36; C09D 153/00 20060101
C09D153/00 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 28, 2014 |
JP |
2014-174490 |
Claims
1. An ink composition comprising: a pigment; a polymer dispersant;
water; and a water-soluble organic solvent, wherein the pigment
includes Pigment Yellow 74, and the integrated value of absorbance
of light having a wavelength of 300 nm to 400 nm is 30% or less
with respect to 100% of the integrated value of absorbance of light
having a wavelength of 300 nm to 600 nm.
2. The ink composition according to claim 1, wherein the integrated
value of absorbance of light having a wavelength of 500 nm to 600
nm is 5.0% or less with respect to 100% of the integrated value of
absorbance of light having a wavelength of 300 nm to 600 nm.
3. The ink composition according to claim 1, wherein the maximum
absorption wavelength of the ink composition is 430 nm to 450
nm.
4. The ink composition according to claim 1, wherein the polymer
dispersant is a polymer having a structural unit derived from a
cycloalkyl group-containing (meth)acrylate.
5. The ink composition according to claim 1, wherein the
water-soluble organic solvent contains 1,2-hexanediol.
6. The ink composition according to claim 1, wherein the ratio
(I.sub.430/I.sub.550) of absorbance of light having a wavelength of
550 nm to absorbance of light having a wavelength of 430 nm is 18
or more.
7. The ink composition according to claim 1, wherein the polymer
dispersant is a graft copolymer and/or a block copolymer including
a polymer chain A and a polymer chain B, the polymer chain A
includes 20 mass % to 60 mass % of a structural unit derived from a
cycloalkyl group-containing (meth)acrylate, 10 mass % to 35 mass %
of a structural unit derived from a (meth)acrylic acid, and 5.0
mass % to 70 mass % of a structural unit derived from a
(meth)acrylate not containing a cycloalkyl group, the polymer chain
A has a number average molecular weight of 1,000 to 10,000, and the
polymer chain B includes 30 mass % to 70 mass % of a structural
unit derived from a cycloalkyl group-containing (meth)acrylate, and
30 mass % to 70 mass % of a structural unit derived from at least
one of a vinyl monomer having an aromatic ring and a (meth)acrylate
having an aromatic ring.
8. An ink set comprising: a yellow ink composition; a cyan ink
composition; and a magenta ink composition, wherein the yellow ink
composition is the ink composition according to claim 1, the cyan
ink composition includes a cyan pigment and a styrene acrylic
polymer dispersant, and the magenta ink composition includes a
magenta pigment and a styrene acrylic polymer dispersant.
9. An ink set comprising: a yellow ink composition; a cyan ink
composition; and a magenta ink composition, wherein the yellow ink
composition is the ink composition according to claim 2, the cyan
ink composition includes a cyan pigment and a styrene acrylic
polymer dispersant, and the magenta ink composition includes a
magenta pigment and a styrene acrylic polymer dispersant.
10. An ink set comprising: a yellow ink composition; a cyan ink
composition; and a magenta ink composition, wherein the yellow ink
composition is the ink composition according to claim 3, the cyan
ink composition includes a cyan pigment and a styrene acrylic
polymer dispersant, and the magenta ink composition includes a
magenta pigment and a styrene acrylic polymer dispersant.
11. An ink set comprising: a yellow ink composition; a cyan ink
composition; and a magenta ink composition, wherein the yellow ink
composition is the ink composition according to claim 4, the cyan
ink composition includes a cyan pigment and a styrene acrylic
polymer dispersant, and the magenta ink composition includes a
magenta pigment and a styrene acrylic polymer dispersant.
12. An ink set comprising: a yellow ink composition; a cyan ink
composition; and a magenta ink composition, wherein the yellow ink
composition is the ink composition according to claim 5, the cyan
ink composition includes a cyan pigment and a styrene acrylic
polymer dispersant, and the magenta ink composition includes a
magenta pigment and a styrene acrylic polymer dispersant.
13. An ink set comprising: a yellow ink composition; a cyan ink
composition; and a magenta ink composition, wherein the yellow ink
composition is the ink composition according to claim 6, the cyan
ink composition includes a cyan pigment and a styrene acrylic
polymer dispersant, and the magenta ink composition includes a
magenta pigment and a styrene acrylic polymer dispersant.
14. An ink set comprising: a yellow ink composition; a cyan ink
composition; and a magenta ink composition, wherein the yellow ink
composition is the ink composition according to claim 7, the cyan
ink composition includes a cyan pigment and a styrene acrylic
polymer dispersant, and the magenta ink composition includes a
magenta pigment and a styrene acrylic polymer dispersant.
Description
BACKGROUND
[0001] 1. Technical Field
[0002] The present invention relates to an ink composition and an
ink set.
[0003] 2. Related Art
[0004] Ink jet recording methods have been rapidly developed in
many areas because high-definition images can be recorded by a
comparatively simple device. Among these, various studies have been
made about the color developing properties and light resistance of
the obtained image. For example, JP-A-2012-72359, for the purpose
of providing an ink which can make the color developing properties
and light resistance of an image excellent and can obtain an image
having a high-level of glossiness, discloses an ink, including a
plurality of pigments, a plurality of water-soluble resins, a
surfactant, and a water-soluble organic solvent, in which the
surfactant is a polyoxyethylene alkyl ether having a HLB value of
13.0 or more, measured by Griffin's method, the plurality of
pigments include C.I. Pigment Yellow 74 and C.I. Pigment Yellow
128, the plurality of water-soluble resins include acrylic resin
and urethane resin, and the water-soluble organic solvent includes
a predetermined compound.
[0005] However, when the ink is used in combination with pigments
as disclosed in JP-A-2012-72359, there is a problem in that the
color balance of an image is apt to collapse in the time-dependent
change because the degree of color fading of each of the pigments
is different.
SUMMARY
[0006] The purpose of this invention is to solve at least a part of
the above-mentioned problem. An advantage of some aspects of the
invention is to provide an ink composition which can obtain an
image having excellent color developing properties and light
resistance and which has excellent storage stability, and an ink
set using the ink composition.
[0007] The present inventors have made efforts to solve the
above-mentioned problems. As a result, the present inventors have
found that these problems can be solved if an ink composition
having a predetermined configuration is used. Based on this
finding, the invention has been completed.
[0008] That is, the invention is as follows.
[0009] [1] An ink composition including: a pigment; a polymer
dispersant; water; and a water-soluble organic solvent, in which
the pigment includes Pigment Yellow 74, and the integrated value of
absorbance of light having a wavelength of 300 nm to 400 nm is 30%
or less with respect to 100% of the integrated value of absorbance
of light having a wavelength of 300 nm to 600 nm.
[0010] [2] The ink composition according to [1], in which the
integrated value of absorbance of light having a wavelength of 500
nm to 600 nm is 5.0% or less with respect to 100% of the integrated
value of absorbance of light having a wavelength of 300 nm to 600
nm.
[0011] [3] The ink composition according to [1] or [2], in which
the maximum absorption wavelength of the ink composition is 430 nm
to 450 nm.
[0012] [4] The ink composition according to any one of [1] to [3],
in which the polymer dispersant is a polymer having a structural
unit derived from a cycloalkyl group-containing (meth)acrylate.
[0013] [5] The ink composition according to any one of [1] to [4],
in which the water-soluble organic solvent contains
1,2-hexanediol.
[0014] [6] The ink composition according to any one of [1] to [5],
in which the ratio (I.sub.430/I.sub.550) of absorbance of light
having a wavelength of 550 nm to absorbance of light having a
wavelength of 430 nm is 18 or more.
[0015] [7] The ink composition according to any one of [1] to [6],
in which the polymer dispersant is a graft copolymer and/or a block
copolymer including a polymer chain A and a polymer chain B, the
polymer chain A includes 20 mass % to 60 mass % of a structural
unit derived from a cycloalkyl group-containing (meth)acrylate, 10
mass % to 35 mass % of a structural unit derived from a
(meth)acrylic acid, and 5.0 mass % to 70 mass % of a structural
unit derived from a (meth)acrylate not containing a cycloalkyl
group, the polymer chain A has a number average molecular weight of
1,000 to 10,000, and the polymer chain B includes 30 mass % to 70
mass % of a structural unit derived from a cycloalkyl
group-containing (meth)acrylate, and 30 mass % to 70 mass % of a
structural unit derived from at least one of a vinyl monomer having
an aromatic ring and a (meth)acrylate having an aromatic ring.
[0016] [8] An ink set including: a yellow ink composition; a cyan
ink composition; and a magenta ink composition, in which the yellow
ink composition is the ink composition according to any one of [1]
to [7], the cyan ink composition includes a cyan pigment and a
styrene acrylic polymer dispersant, and the magenta ink composition
includes a magenta pigment and a styrene acrylic polymer
dispersant.
BRIEF DESCRIPTION OF THE DRAWING
[0017] The invention will be described with reference to the
accompanying drawings, wherein like reference numerals refer to the
like elements.
[0018] FIG. 1 shows charts of absorption wavelengths of ink
compositions of Examples 3 and 4 and Comparative Example 4. Other
Examples are also similar to Examples 3 and 4.
DESCRIPTION OF EXEMPLARY EMBODIMENTS
[0019] Hereinafter, an embodiment of the invention (hereinafter,
referred to as "present embodiment") will be described in detail,
but the invention is not limited thereto. Various modifications can
be made within the scope not departing from the gist thereof. In
the present specification, "(meth)acrylate" means both acrylate and
methacrylate corresponding thereto.
Ink Composition
[0020] The ink composition of yellow ink according to the present
embodiment includes a pigment; a polymer dispersant; water; and a
water-soluble organic solvent, in which the pigment includes
Pigment Yellow 74, and the integrated value of absorbance of light
having a wavelength of 300 nm to 400 nm is 30% or less with respect
to 100% of the integrated value of absorbance of light having a
wavelength of 300 nm to 600 nm.
Absorbance
[0021] The integrated value of absorbance of light having a
wavelength of 300 nm to 400 nm in the ink composition of yellow ink
is 30% or less, preferably 0% to 25%, and more preferably 0% to
20%, with respect to 100% of the integrated value of absorbance of
light having a wavelength of 300 nm to 600 nm. When the integrated
value of absorbance of light having a wavelength of 300 nm to 400
nm is within the above range, light resistance is further improved.
The reason for this is because the absorption wavelength of the
Pigment Yellow 74-containing yellow ink is shifted to a
long-wavelength region to avoid the ultraviolet region as much as
possible. The integrated value of absorbance of light having a
wavelength of 300 nm to 400 nm in the ink composition of yellow ink
can be measured by the methods described in Examples.
[0022] In addition, the integrated value of absorbance of light
having a wavelength of 500 nm to 600 nm in the ink composition of
yellow ink is preferably 10.0% or less, more preferably 0% to 8.0
mass %, and further preferably 0% to 5.0%, with respect to 100% of
the integrated value of absorbance of light having a wavelength of
300 nm to 600 nm. When the integrated value of absorbance of light
having a wavelength of 500 nm to 600 nm in yellow ink is within the
above range, green color developing properties tend to be further
improved when yellow ink is combined with magenta ink and cyan ink
et al. to be used as an ink set. The integrated value of absorbance
of light having a wavelength of 500 nm to 600 nm in the ink
composition can be measured by the methods described in
Examples.
[0023] Meanwhile, the ratio (I.sub.430/I.sub.550) of the absorbance
of light having a wavelength of 550 nm to the absorbance of light
having a wavelength of 430 nm in the ink composition of yellow ink
is preferably 10 or more, more preferably 20 or more, and further
preferably 30 or more. The upper limit of the ratio
(I.sub.430/I.sub.550) is not particularly limited, but the larger
it is, the more preferable. More preferably, the upper limit
thereof is 1000. When the ratio (I.sub.430/I.sub.550) is within the
above range, color reproducibility tends to be further wider.
Maximum Absorption Wavelength
[0024] The maximum absorption wavelength of the ink composition of
yellow ink is preferably 420 nm to 450 nm, more preferably 425 nm
to 445 nm, and further preferably 430 nm to 440 nm. The maximum
absorption wavelength of the ink composition of yellow ink can be
measured by the methods described in Examples.
Pigment
[0025] The pigment includes Pigment Yellow 74. When yellow ink
contains Pigment Yellow 74, yellow color developing properties are
further improved. The yellow ink may contain other yellow pigments
as the pigment in addition to Pigment Yellow 74. Other yellow
pigments are not particularly limited, but examples thereof include
C.I. Pigment Yellows 1, 2, 3, 4, 5, 6, 7, 10, 11, 12, 13, 14, 16,
17, 24, 34, 35, 37, 53, 55, 65, 73, 75, 81, 83, 93, 94, 95, 97, 98,
99, 108, 109, 110, 113, 114, 117, 120, 124, 128, 129, 133, 138,
139, 147, 151, 153, 154, 167, 172, and 180.
[0026] The content of the pigment is preferably 1 mass % to 10 mass
%, more preferably 2 mass % to 8 mass %, and further preferably 3
mass % to 6 mass %, with respect to the total amount of the ink
composition. When the content of the pigment is less than 1 mass %,
sufficient color development cannot be obtained. Further, when the
content of the pigment is more than 10.0 mass %, ejection stability
deteriorates.
Polymer Dispersant
[0027] The polymer dispersant is not particularly limited, but
examples thereof include polyvinyl alcohols, polyvinyl
pyrrolidones, a polyacrylic acid, an acrylic acid-acrylonitrile
copolymer, a vinyl acetate-acrylic ester copolymer, an acrylic
acid-acrylic ester copolymer, a styrene-acrylic acid copolymer, a
styrene-methacrylic acid copolymer, a styrene-methacrylic
acid-acrylic ester copolymer, a styrene-.alpha.-methyl
styrene-acrylic acid copolymer, a styrene-.alpha.-methyl
styrene-acrylic acid-acrylic ester copolymer, a styrene-maleic acid
copolymer, a styrene-maleic anhydride copolymer, a vinyl
naphthalene-acrylic acid copolymer, a vinyl naphthalene-maleic acid
copolymer, a vinyl acetate-maleic ester copolymer, a vinyl
acetate-crotonic acid copolymer, a vinyl acetate-acrylic acid
copolymer, and salts thereof. Among these, particularly, copolymers
of monomers having a hydrophobic functional group and monomers
having a hydrophilic functional group, and polymers composed of
monomers having both a hydrophobic functional group and a
hydrophilic functional group are preferable. As the form of the
copolymer, any form of a random copolymer, a block copolymer, an
alternating copolymer, and a graft copolymer can be used.
[0028] Among these, as the polymer dispersant, a polymer having a
structural unit derived from a cycloalkyl group-containing
(meth)acrylate is preferable. When such a polymer dispersant is
used, the refractive index of the polymer dispersant increases, and
the amount of ultraviolet light absorbed by the pigment decreases,
so that light resistance tends to be further improved. In addition,
when such a polymer dispersant is used, the absorption wavelength
of the ink composition is changed, and, in the case where the
polymer dispersant is used as an ink set, the amount of red
components is reduced, and green color saturation tends to be
further improved.
[0029] Among these, as the polymer dispersant, a graft copolymer
and/or a block copolymer including the following polymer chain A
and the following polymer chain B is preferable. Specific examples
of the graft copolymer and/or the block copolymer include graft
copolymers including a polymer chain A grafted with a plurality of
polymer chains B, graft copolymers including a polymer chain B
grafted with a plurality of polymer chains A, and block copolymers
having a block including the polymer chain A and a block including
the polymer chain B. The block copolymers are not particularly
limited, but examples thereof include di-block copolymers,
tetra-block copolymers, and hexa-block copolymers. When such a
polymer dispersant is used, light resistance and color developing
properties tend to be further improved.
Polymer Chain A
[0030] The polymer chain A includes 20 mass % to 60 mass % of a
structural unit derived from a cycloalkyl group-containing
(meth)acrylate, 10 mass % to 35 mass % of a structural unit derived
from a (meth)acrylic acid, and 5 mass % to 70 mass % of a
structural unit derived from a (meth)acrylate not containing a
cycloalkyl group. The carboxyl group contained in the structural
unit derived from a (meth)acrylic acid is ionized by being
neutralized with an alkali. Therefore, the polymer chain A
including the structural unit derived from a (meth)acrylic acid is
relatively hydrophilic compared to the polymer chain B, and
contributes to the dispersibility of the pigment.
[0031] The cycloalkyl group-containing (meth)acrylate is not
particularly limited, but examples thereof include cyclohexyl
(meth)acrylate, methylcyclohexyl (meth)acrylate,
3,3,5-trimethylcyclohexyl (meth)acrylate, t-butylcyclohexyl
(meth)acrylate, cyclohexyloxyethyl (meth)acrylate, tricyclodecyl
(meth)acrylate, and isobornyl (meth)acrylate. Among these,
cyclohexyl (meth)acrylate and 3,3,5-trimethylcyclohexyl
(meth)acrylate are preferable. When such a cycloalkyl
group-containing (meth)acrylate is used, light resistance and color
developing properties tend to be further improved. These cycloalkyl
group-containing (meth)acrylates may be used alone or in
combination with two or more thereof.
[0032] The carbon number of a cycloalkyl group is preferably 6 to
9. When the carbon number of a cycloalkyl group is within the above
range, light resistance and color developing properties tend to be
further improved.
[0033] The content of the structural unit derived from the
cycloalkyl group-containing (meth)acrylate is preferably 20 mass %
to 60 mass %, and more preferably 30 mass % to 50 mass %, with
respect to 100 mass % of the polymer chain A. When the content of
the structural unit derived from the cycloalkyl group-containing
(meth)acrylate is 20 mass % or more, light resistance and color
developing properties tend to be further improved. Further, when
the content of the structural unit derived from the cycloalkyl
group-containing (meth)acrylate is 60 mass % or more, the
dispersion stability of the pigment deteriorates.
[0034] The content of the structural unit derived from the
(meth)acrylic acid is preferably 10 mass % to 35 mass %, and more
preferably 15 mass % to 25 mass %, with respect to 100 mass % of
the polymer chain A. When the content of the structural unit
derived from the (meth)acrylic acid is 10 mass % or more,
water-solubility tends to be further improved. Further, when the
content of the structural unit derived from the (meth)acrylic acid
is 35 mass % or less, the water resistance of the printed matter
tends to be further improved. The carboxyl group of a (meth)acrylic
acid may form bases and salts.
[0035] The (meth)acrylate not containing a cycloalkyl group is not
particularly limited, but examples thereof include: aliphatic alkyl
(meth)acrylates, such as methyl (meth)acrylate, butyl
(meth)acrylate, and dodecyl (meth)acrylate; aromatic
(meth)acrylates, such as phenyl (meth)acrylate and benzyl
(meth)acrylate; hydroxyl group-containing (meth)acrylate, such as
2-hydroxyethyl (meth)acrylate and 2-hydroxypropyl (meth)acrylate;
ether group or chain-containing (meth)acrylates, such as (poly)
ethylene glycol monoalkyl ether (meth)acrylate; and amino
group-containing (meth)acrylates, such as dimethylaminoethyl
(meth)acrylate. These (meth)acrylates not containing a cycloalkyl
group may be used alone or in combination with two or more
thereof.
[0036] The content of the structural unit derived from the
(meth)acrylate not containing a cycloalkyl group is 5.0 mass % to
70 mass % with respect to 100 mass % of the polymer chain A.
[0037] The number average molecular weight of the polymer chain A
is preferably 1,000 to 10,000, and more preferably 2,000 to 7,000.
When the number average molecular weight of the polymer chain A is
1,000 or less, the rate of hydrophilic portions occupying the
polymer dispersant becomes low, so that sufficient steric repulsion
cannot be obtained, and thus dispersion stability of the pigment
deteriorates. Further, when the number average molecular weight of
the polymer chain A is 10,000 or more, the ratio of hydrophilic
portion occupying the polymer dispersant becomes high, so that a
polymer is detached from the surface of the pigment, and thus the
dispersion stability of the pigment deteriorates. Here, the number
average molecular weight can be obtained as the polystyrene
conversion molecular weight by using gel permeation chromatography
(hereinafter, referred to as "GPC").
[0038] The content of the polymer chain A is preferably mass % to
70 mass %, more preferably 40 mass % to 60 mass %, and further
preferably 40 mass % to 50 mass %, with respect to 100 mass % of
the total amount of the polymer dispersant. When the content of the
polymer chain A is mass % or more, the steric repulsion of the
polymer dispersant becomes sufficient, and thus the dispersion
stability of the pigment tends to be further improved. In contrast,
when the content of the polymer chain A is 70 mass % or more, the
polymer dispersant is detached from the surface of the pigment, and
thus the dispersion stability of the pigment deteriorates.
Polymer Chain B
[0039] The polymer chain B includes 30 mass % to 70 mass % of a
structural unit derived from a cycloalkyl group-containing
(meth)acrylate, and 30 mass % to 70 mass % of a structural unit
derived from at least one of a vinyl monomer having an aromatic
ring and a (meth)acrylate having an aromatic ring. The polymer
chain B is relatively hydrophobic compared to the polymer chain A,
and can be adsorbed on the pigment by hydrophobic interaction to
coat (encapsulate) the pigment.
[0040] The cycloalkyl group-containing (meth)acrylate is not
particularly limited, but examples thereof include those
exemplified in the polymer chain A. The cycloalkyl group-containing
(meth)acrylate exemplified in the polymer chain A may be the same
as or different from the cycloalkyl group-containing (meth)acrylate
of the polymer chain B. Among these, cyclohexyl (meth)acrylate and
3,3,5-trimethylcyclohexyl (meth)acrylate are preferable. When such
a cycloalkyl group-containing (meth)acrylate is used, the
dispersion stability of the pigment tends to be further
improved.
[0041] The content of the structural unit derived from the
cycloalkyl group-containing (meth)acrylate is preferably 30 mass %
to 70 mass %, and more preferably 40 mass % to 60 mass %, with
respect to 100 mass % of the polymer chain B. When the content of
the structural unit derived from the cycloalkyl group-containing
(meth)acrylate is 30 mass % or more, the polymer dispersant is
easily adsorbed on the surface of the pigment, and thus the
dispersion stability of the pigment tends to be further improved.
Further, when the content of the structural unit derived from the
cycloalkyl group-containing (meth)acrylate is more than 70 mass %,
the hydrophobicity of the polymer dispersant becomes high, and
thus, conversely, the dispersion stability of the pigment tends to
deteriorate.
[0042] The vinyl monomer having an aromatic ring is not
particularly limited, but examples thereof include vinyl toluene
and vinyl naphthalene. When such a vinyl monomer having an aromatic
ring is used, the adsorptivity of the polymer dispersant onto the
surface of the pigment tends to be further improved.
[0043] The content of the structural unit derived from the vinyl
monomer having an aromatic ring is preferably 30 mass % to 70 mass
%, and more preferably 40 mass % to 60 mass %, with respect to 100
mass % of the polymer chain B. When the content of the structural
unit derived from the vinyl monomer having an aromatic ring is 30
mass % or more, the polymer dispersant is easily adsorbed on the
surface of the pigment, and thus the dispersion stability of the
pigment tends to be further improved. Further, when the content of
the structural unit derived from the vinyl monomer having an
aromatic ring is more than 70 mass %, the hydrophobicity of the
polymer dispersant becomes high, and thus, conversely, the
dispersion stability of the pigment tends to deteriorate.
[0044] The (meth)acrylate having an aromatic ring is not
particularly limited, but examples thereof include phenyl
(meth)acrylate, naphthoxy (meth)acrylate, benzyl (meth)acrylate,
phenoxyethyl (meth)acrylate, and para-cumylphenol ethylene
oxide-modified (meth)acrylate. When such a (meth)acrylate having an
aromatic ring is used, the pigment coverage of the polymer
dispersant tends to be further improved.
[0045] The content of the structural unit derived from the
(meth)acrylate having an aromatic ring is preferably 30 mass % to
70 mass %, and more preferably 40 mass % to 60 mass %, with respect
to 100 mass % of the polymer chain B. When the content of the
structural unit derived from the (meth)acrylate having an aromatic
ring is 30 mass % or more, the polymer dispersant is easily
adsorbed on the surface of the pigment, and thus the dispersion
stability of the pigment tends to be further improved. Further,
when the content of the structural unit derived from the
(meth)acrylate having an aromatic ring is more than 70 mass %, the
hydrophobicity of the polymer dispersant becomes high, and thus,
conversely, the dispersion stability of the pigment tends to
deteriorate.
[0046] The total content of the structural unit derived from the
vinyl monomer having an aromatic ring and the structural unit
derived from the (meth)acrylate having an aromatic ring is
preferably 30 mass % to 70 mass %, and more preferably 40 mass % to
60 mass %, with respect to 100 mass % of the polymer chain B. When
the total content of the structural unit derived from the vinyl
monomer having an aromatic ring and the structural unit derived
from the (meth)acrylate having an aromatic ring is 30 mass % or
more, the polymer dispersant is easily adsorbed on the surface of
the pigment, and thus the dispersion stability of the pigment tends
to be further improved. Further, when the total content of the
structural unit derived from the vinyl monomer having an aromatic
ring and the structural unit derived from the (meth)acrylate having
an aromatic ring is more than 70 mass %, the hydrophobicity of the
polymer dispersant becomes high, and thus, conversely, the
dispersion stability of the pigment tends to deteriorate.
[0047] The polymer chain B may include a structural unit derived
from a (meth)acrylate not containing a cycloalkyl group. The
(meth)acrylate not containing a cycloalkyl group is not
particularly limited, but examples thereof include those
exemplified in the polymer chain A. The (meth)acrylate not
containing a cycloalkyl group exemplified in the polymer chain A
may be the same as or different from the (meth)acrylate not
containing a cycloalkyl group of the polymer chain B.
[0048] The number average molecular weight of the polymer
dispersant is preferably 2,000 to 20,000, more preferably 5,000 to
15,000, and further preferably 7,000 to 12,000. When the number
average molecular weight thereof is 2,000 or less, dispersion
stability deteriorates. Further, when the number average molecular
weight thereof is 20,000 or more, the viscosity of a dispersion
liquid becomes high, and thus the dispersion of the pigment does
not proceed at the time of the preparation of the dispersion
liquid.
Synthesis Method of Graft Copolymer
[0049] The graft copolymer can be synthesized based on methods
known in the related art. Specific examples of the methods known in
the related art include: a macromonomer method of polymerizing a
macromonomer (polymer chain A) having an unsaturated bond for
radical polymerization at one terminal thereof with a monomer which
is a constituent of polymer chain B; a side chain polymerization
method of polymerizing monomers, which are constituents of polymer
chain A, in the presence of polymer chain B bonded with a
polymerization initiating group; and a polymer reaction method, in
which polymer chain A having reactive group "X" introduced at one
terminal is polymerized with a monomer having functional group "Y"
capable of reacting with the reactive group "X" to prepare polymer
chain B having functional group "Y" at the side chain thereof, and
the polymer chain A and polymer chain B are reacted. The graft
copolymer can be synthesized by any of these synthesis methods,
but, among these, the macromonomer method is preferable.
[0050] The macromonomer can be synthesized based on methods known
in the related art. Specific examples of the methods known in the
related art include: a method of polymerizing (meth)acrylate along
with depolymerization at high temperature and high pressure to
introduce an unsaturated bond at a terminal; a method of
introducing a hydroxyl group at a terminal using a chain transfer
agent having a functional group, such as a thiol group or a
hydroxyl group, and reacting a monomer having a functional group
capable of reacting with the introduced hydroxyl group; a method of
performing irreversible addition cleavage chain transfer
polymerization using a vinyl monomer (for example, an
.alpha.-bromomethyl acrylate-based compound, an
.alpha.-methylstyrene dimer, or a methyl methacrylate dimer) having
an easily detachable group as a radical at the position .alpha., as
a chain transfer agent; and, in the following living radical
polymerization method, a method of obtaining a macromonomer by
obtaining a polymer using a polymerization initiating compound
having a functional group such as a hydroxyl group or a halogen and
adding a compound having an unsaturated bond capable of reacting
with the functional group to introduce an unsaturated bond at a
terminal.
[0051] When the macromonomer obtained in this way is polymerized
with the monomer, which is a constituent of the polymer chain B,
based on a method known in the related art, such as a general
radical polymerization method or the following living radical
polymerization method, it is possible to obtain a targeted graft
copolymer.
Synthesis Method of Block Copolymer
[0052] The synthesis method of a block copolymer is not
particularly limited, but examples thereof include a living
cationic polymerization method, a living anionic polymerization
method, and a living radical polymerization method.
[0053] Specific examples of the living radical polymerization
method include: an NMP method in which a compound capable of
producing a nitroxide radical is used; an ATRP method in which a
halogenated compound is used as a polymerization initiating
compound, and polymerization is livingly performed from the
polymerization initiating compound using a metal complex such as a
copper complex or a ruthenium complex; a RAFT method in which a
dithiocarboxylic ester or a xanthate compound is used; a TERP
method in which an organic tellurium compound is used as a
polymerization initiating compound; and a RTCP method in which an
iodine compound is used as a polymerization initiating compound,
and a phosphorus compound, a nitrogen compound, a carbon compound,
or an oxygen compound is used as a catalyst.
[0054] These living radical polymerization methods can be carried
out under polymerization conditions known in the related art. For
example, the living radical polymerization may be carried out under
a condition of bulk polymerization, suspension polymerization,
emulsion polymerization, or solution polymerization. Here, in the
case of solution polymerization, the reaction solution after
polymerization may be directly used as a solution of a polymer
dispersant, the solvent having been used for polymerization may be
replaced with another solvent, and only a block copolymer may be
extracted by performing precipitation one time in a poor solvent.
Among these, it is preferable that solution polymerization is
carried out by using the organic solvent contained in the ink jet
ink as a solvent for polymerization. Therefore, only by adding an
alkali to the reaction solution after polymerization to neutralize
a block copolymer, the block copolymer can be easily used as a
polymer dispersant.
[0055] When the graft copolymer or block copolymer, obtained as
described above, is neutralized (made into an aqueous solution)
with an alkali, it can be used as the polymer dispersant. Specific
examples of the alkali may include: ammonia; alkylamines, such as
trimethylamine and triethylamine; glycol-based amines, such as
diethanolamine and triethanolamine; cyclic amines, such as
morpholine and pyridine; and hydroxides, such as sodium hydroxide
and potassium hydroxide. It is preferable that the amount of the
alkali used is the molar equivalent or more of a carboxyl group
contained in the graft copolymer or block copolymer.
Water
[0056] Examples of water include water from which ionic impurities
are removed as many as possible, for example, pure water or
ultrapure water such as ion exchange water, ultra-filtrated water,
reverse osmosis water, and distilled water. In addition, when water
sterilized by irradiation with ultraviolet light, the addition of
hydrogen peroxide, or the like, is used, it is possible to prevent
the generation of mold or bacteria during long-term storage of the
ink. Accordingly, the storage stability of the ink composition
tends to be further improved.
[0057] The content of water is preferably 50 mass % to 90 mass %,
and more preferably 60 mass % to 80 mass %, with respect to the
total amount of the ink composition.
Water-Soluble Organic Solvent
[0058] The water-soluble organic solvent is not particularly
limited, but examples thereof include alcohols or glycols such as
glycerin, ethylene glycol, diethylene glycol, triethylene glycol,
propylene glycol, dipropylene glycol, 1,3-propanediol,
1,2-butanediol, 1,2-pentanediol, 1,2-hexanediol, 1,4-butanediol,
1,5-pentanediol, 1,6-hexanediol, diethylene glycol mono-n-propyl
ether, ethylene glycol mono-iso-propyl ether, diethylene glycol
mono-iso-propyl ether, ethylene glycol mono-n-butyl ether, ethylene
glycol mono-t-butyl ether, diethylene glycol mono-n-butyl ether,
triethylene glycol monobutyl ether, diethylene glycol mono-t-butyl
ether, propylene glycol monomethyl ether, propylene glycol
monoethyl ether, propylene glycol mono-t-butyl ether, propylene
glycol mono-n-propyl ether, propylene glycol mono-iso-propyl ether,
propylene glycol mono-n-butyl ether, dipropylene glycol
mono-n-butyl ether, dipropylene glycol mono-n-propyl ether,
dipropylene glycol mono-iso-propyl ether, diethylene glycol
dimethyl ether, diethylene glycol diethyl ether, diethylene glycol
dibutyl ether, diethylene glycol ethyl methyl ether, diethylene
glycol butyl methyl ether, triethylene glycol dimethyl ether,
tetraethylene glycol dimethyl ether, dipropylene glycol dimethyl
ether, dipropylene glycol diethyl ether, tripropylene glycol
dimethyl ether, methanol, ethanol, n-propyl alcohol, iso-propyl
alcohol, n-butanol, 2-butanol, tert-butanol, iso-butanol,
n-pentanol, 2-pentanol, 3-pentanol, and tert-pentanol;
N,N-dimethylformamide; N,N-dimethylacetamide; 2-pyrrolidone;
N-methyl-2-pyrrolidone; 2-oxazolidone;
1,3-dimethyl-2-imidazolidinone; dimethyl sulfoxide; sulfolane; and
1,1,3,3-tetramethyl urea. These water-soluble organic solvents may
be used alone or in combination with two or more thereof.
[0059] Among these, 1,2-hexanediol, diethylene glycol mono-n-butyl
ether, and triethylene glycol mono-n-butyl ether are preferable,
and 1,2-hexanediol is more preferable. When such a water-soluble
organic solvent is used, the permeability of the ink composition
into a medium tends to be further improved.
[0060] The content of the water-soluble organic solvent is
preferably 5 mass % to 30 mass %, and more preferably 10 mass % to
20 mass %, with respect to the total amount of the ink composition.
When the content of the water-soluble organic solvent is within the
above range, the dispersion stability of the pigment and the
suppression of the evaporation and thickening of the ink
composition in the vicinity of a nozzle are compatible with each
other.
Surfactant
[0061] The ink composition of the present embodiment may further
contains a surfactant. The surfactant is not particularly limited,
but examples thereof include an acetylene glycol-based surfactant,
a fluorine-based surfactant, and a silicone-based surfactant. Among
these, the silicone-based surfactant is preferable.
[0062] The acetylene glycol-based surfactant is not particularly
limited, but preferable examples thereof include one or more
selected from an alkylene oxide adduct of
2,4,7,9-tetramethyl-5-decyne-4,7-diol and an alkylene oxide adduct
of 2,4,7,9-tetramethyl-5-decyne-4,7-diol, and an alkylene oxide
adduct of 2,4-dimethyl-5-decyne-4-ol and an alkylene oxide adduct
of 2,4-dimethyl-5-decyne-4-ol. The commercially available products
of the acetylene glycol-based surfactant are not particularly
limited, but examples thereof include an Olfine 104 series or an E
series such as Olfine E1010 (trade name, manufactured by Air
Products Japan, Inc.), and Surfynol 465 or Surfynol 61 (trade name,
manufactured by Nissin Chemical Industry Co., Ltd.). The acetylene
glycol-based surfactants may be used alone or in combination of two
or more thereof.
[0063] The fluorine-based surfactant is not particularly limited,
but examples thereof include perfluoroalkyl sulfonate ester,
perfluoroalkyl carboxylate, perfluoroalkyl phosphate, a
perfluoroalkyl ethylene oxide adduct, perfluoroalkyl betaine, and a
perfluoroalkyl amine oxide compound. The commercially available
products of the fluorine-based surfactant are not particularly
limited, but examples thereof include S-144 and S-145 (manufactured
by Asahi Glass Co., Ltd.); FC-170C, FC-430, and Fluorad-FC4430
(manufactured by Sumitomo 3M, Ltd.); FSO, FSO-100, FSN, FSN-100,
and FS-300 (manufactured by Dupont Co.); and FT-250 and FT-251
(Neos Co., Ltd.). The fluorine-based surfactants may be used alone
or in combination of two or more thereof.
[0064] The silicone-based surfactant is not particularly limited,
but examples thereof include a polysiloxane-based compound,
polyether-modified organosiloxane, and the like. The commercially
available products of the silicone-based surfactant are not
particularly limited, but specific examples thereof include
BYK-306, BYK-307, BYK-333, BYK-341, BYK-345, BYK-346, BYK-347,
BYK-348, and BYK-349 (trade names, manufactured by BYK Japan K.K.);
and KF-351A, KF-352A, KF-353, KF-354L, KF-355A, KF-615A, KF-945,
KF-640, KF-642, KF-643, KF-6020, X-22-4515, KF-6011, KF-6012,
KF-6015, and KF-6017 (trade names, manufactured by Shin-Etsu
Chemical Co., Ltd.).
[0065] The content of the surfactant is preferably 0.1 mass % to
5.0 mass %, and more preferably 0.2 mass % to 3.0 mass %, with
respect to the total mass of the ink composition. When the content
of the surfactant is within the above range, the filling ability of
a printer with ink and the wettability of ink into a medium tend to
be further improved.
Other Components
[0066] The ink composition used in the present embodiment, if
necessary, may further contain various additives, such as
dissolution aids, viscosity modifiers, pH adjusting agents,
antioxidants, preservatives, anti-mold agents, corrosion
inhibitors, and chelating agents for capturing a metal ion that
influences the dispersion.
Ink Set
[0067] The ink set of the present embodiment includes yellow ink,
cyan ink, and magenta ink. Here, the yellow ink is composed of the
above ink composition, the cyan ink contains a cyan pigment and a
styrene acrylic polymer dispersant, and the magenta ink contains a
magenta pigment and a styrene acrylic polymer dispersant. When the
ink set contains the styrene acrylic polymer dispersant, there is
an effect of fixing and dispersing. When the above ink composition
is used as the yellow ink, the color saturation and light
resistance of the obtained recorded matter are further improved. In
addition, in the cyan ink and the magenta ink, when the styrene
acrylic polymer dispersant is used, the color saturation of the
obtained recorded matter is further improved. Since each of the
cyan pigment and the magenta pigment generally has excellent light
resistance compared to the yellow pigment, it is preferable to use
the styrene acrylic polymer dispersant rather than the above
dispersant, from the viewpoint of color saturation being further
improved. Meanwhile, since the yellow pigment has a relatively low
light resistance, when the above ink composition is used, both
light resistance and color saturation can be improved.
Yellow Ink
[0068] Yellow ink is the above ink composition.
Cyan Ink
[0069] Cyan ink contains a cyan pigment and a styrene acrylic
polymer dispersant, and, if necessary, may further include water, a
water-soluble organic solvent, a surfactant, and other
components.
[0070] The cyan pigment is not particularly limited, but examples
thereof include C.I. Pigment Blues 1, 2, 3, 15, 15:1, 15:2, 15:3,
15:34, 15:4, 16, 18, 22, 25, 60, 65, and 66, and C.I. Vat Blues 4
and 60.
[0071] The styrene acrylic polymer dispersant contained in the cyan
ink is not particularly limited, but examples thereof include
styrene-acrylic resins, such as a styrene-acrylic acid copolymer, a
styrene-methacrylic acid copolymer, a styrene-methacrylic
acid-acrylic ester copolymer, a styrene-.alpha.-methyl
styrene-acrylic acid copolymer, and a styrene-.alpha.-methyl
styrene-acrylic acid-acrylic acid ester copolymer. When the styrene
acrylic polymer dispersant is used in the cyan ink, the dispersion
stability of the pigment is further improved.
[0072] Water, a water-soluble organic solvent, a surfactant, and
other components are not particularly limited, but examples thereof
include those exemplified above. The water-soluble organic solvent,
surfactant, and other components used in the cyan ink may be the
same as or different from those used in the yellow ink.
Magenta Ink
[0073] Magenta ink includes a magenta pigment and a styrene acrylic
polymer dispersant, and, if necessary, may further include water, a
water-soluble organic solvent, a surfactant, and other
components.
[0074] The magenta pigment is not particularly limited, but
examples thereof include C.I. Pigment Reds 1, 2, 3, 4, 5, 6, 7, 8,
9, 10, 11, 12, 14, 15, 16, 17, 18, 19, 21, 22, 23, 30, 31, 32, 37,
38, 40, 41, 42, 48 (Ca), 48 (Mn), 57 (Ca), 57:1, 88, 112, 114, 122,
123, 144, 146, 149, 150, 166, 168, 170, 171, 175, 176, 177, 178,
179, 184, 185, 187, 202, 209, 219, 224, and 245, and C.I. Pigment
Violets 19, 23, 32, 33, 36, 38, 43, and 50.
[0075] The styrene acrylic polymer dispersant, water, water-soluble
organic solvent, surfactant, and other components contained in the
magenta ink are not particularly limited, but examples thereof are
the same as those exemplified above. The water-soluble organic
solvent, surfactant, and other components used in the magenta ink
composition may be the same as or different from those used in the
cyan ink composition. When the styrene acrylic polymer dispersant
is used in the magenta ink composition, the dispersion stability of
the pigment is further improved.
EXAMPLES
[0076] Hereinafter, the invention will be described in detail using
Examples and Comparative Examples. The invention is not limited to
the following Examples.
Materials for Ink Composition
[0077] Main materials for the ink compositions used in the
following Examples and Comparative Examples are as follows.
Pigment
[0078] Pigment Yellow 74 (trade name "Seika Fast Yellow 2016G",
manufactured by Dainichiseika Color & Chemicals Mfg. Co., Ltd.)
(used in yellow ink)
[0079] Pigment Red 122 (trade name "Cyanine Blue A220JC,
manufactured by Dainichiseika Color & Chemicals Mfg. Co., Ltd.)
(used in magenta ink)
[0080] Pigment Blue 15:3 (trade name "CFR130P", manufactured by
Dainichiseika Color & Chemicals Mfg. Co., Ltd.) (used in cyan
ink)
Polymer Dispersant
Graft Copolymer
[0081] Graft copolymer G1 (produced in Synthesis Example 3
below)
[0082] Graft copolymer G2 (produced in Synthesis Example 4
below)
[0083] Graft copolymer G3 (produced in Synthesis Example 5
below)
[0084] Graft copolymer G4 (produced in Comparative Synthesis
Example 3 below)
[0085] Graft copolymer G5 (produced in Comparative Synthesis
Example 4 below)
[0086] Graft copolymer G6 (produced in Comparative Synthesis
Example 5 below)
[0087] Random copolymer R1 (produced in Comparative Synthesis
Example 6 below) Block copolymer
[0088] Block copolymer B1 (produced in Synthesis Example 6
below)
[0089] Block copolymer B2 (produced in Synthesis Example 7
below)
[0090] Block copolymer B3 (produced in Synthesis Example 8
below)
[0091] Block copolymer B4 (produced in Comparative Synthesis
Example 7 below)
[0092] Random copolymer R2 (produced in Comparative Synthesis
Example 8 below)
Water-Soluble Organic Solvent
[0093] Glycerin (manufactured by Kanto Chemical Co., Inc.)
[0094] 1,2-hexanediol (manufactured by Kanto Chemical Co.,
Inc.)
[0095] Triethylene glycol (manufactured by Kanto Chemical Co.,
Inc.)
[0096] Triethanolamine (manufactured by Kanto Chemical Co.,
Inc.)
Surfactant
[0097] BYK-348 (manufactured by BYK Japan K.K.)
[0098] Hereinafter, a method of synthesizing a macromonomer used in
the synthesis of a graft copolymer, a method of synthesizing a
graft copolymer, and a method of synthesizing a block copolymer
will be described.
Synthesis of Macromonomer
Synthesis Example 1
Macromonomer M2
[0099] 250 parts of tripropylene glycol monomethyl ether
(hereinafter, referred to as "MFTG"), 30 parts of MMA, 40 parts of
CHMA, 30 parts of MAA, 2.5 parts of EBMA, and 1 part of V-601 were
put into a reaction container provided with a stirrer, a reflux
condenser, a thermometer, and a nitrogen inlet tube. Polymerization
was carried out at 75.degree. C. for 3 hours while performing
nitrogen bubbling, and then 0.5 parts of V-601 was added thereto.
Polymerization was further carried out for 4.5 hours to obtain a
polymer solution containing a polymer (macromonomer M2). When the
obtained polymer solution was sampled, solid content concentration
was measured, and a polymerization conversion rate was calculated
from non-volatile content, the polymerization conversion rate was
100%. The number average molecular weight (hereinafter, referred to
as "Mn") of the macromonomer M2, measured by a differential
refractometer (hereinafter, referred to as "RI") of GPC, was 6,400,
the weight average molecular weight thereof (hereinafter, referred
to as "Mw") was 10,200, and the dispersion degree (Mw/Mn) thereof
(hereinafter, referred to as "PDI") was 1.59. Meanwhile, peaks were
hardly observed with an ultraviolet absorption detector
(wavelength: 254 nm) (hereinafter, referred to as "UV
detector").
[0100] The obtained polymer solution was poured into a large amount
of water to precipitate a polymer, followed by filtering and
cleaning. After being dissolved in THF, the polymer solution was
poured into a large amount of water again to precipitate a polymer,
followed by filtering and cleaning. Drying was carried out at
50.degree. C. for 24 hours by a dryer to obtain a polymer. When the
1H-NMR of the obtained polymer was measured using a nuclear
magnetic resonance apparatus, the peak of a monomer and the peak of
a proton of an unsaturated bond derived from EBMA were observed at
6 ppm and 6.4 ppm, respectively. Therefore, the obtained polymer is
considered to be a macromonomer having an unsaturated bond at the
terminal thereof. Even in the following Synthesis Examples, it was
confirmed that the polymer obtained by performing the same
measurement is a macromonomer.
Synthesis Example 2
Macromonomer M3
[0101] 250 parts of MFTG, 20 parts of MMA, 15 parts of ethyl
methacrylate (hereinafter, referred to as "EMA"), 5 parts of
hydroxyethyl methacrylate (hereinafter, referred to as "HEMA"), 40
parts of CHMA, 20 parts of MAA, 3.5 parts of EBMA, and 1 part of
V-601 were put into a reaction container provided with a stirrer, a
reflux condenser, a thermometer, and a nitrogen inlet tube.
Polymerization was carried out at 75.degree. C. for 3 hours while
performing nitrogen bubbling, and then 0.5 parts of V-601 was added
thereto. Polymerization was further carried out for 4.5 hours to
obtain a polymer solution containing a polymer (macromonomer M3).
When the obtained polymer solution was sampled, solid content
concentration was measured, and a polymerization conversion rate
was calculated from non-volatile content, the polymerization
conversion rate was 100%. Further, in this case, the Mn of the
macromonomer M3 was 5,700, the Mw thereof was 9,700, and the PDI
thereof was 1.70.
Comparative Synthesis Example 1
Macromonomer M4
[0102] 250 parts of MFTG, 36 parts of MMA, 40 parts of butyl
methacrylate (hereinafter, referred to as "BMA"), 24 parts of MAA,
2.5 parts of EBMA, and 1 part of V-601 were put into a reaction
container provided with a stirrer, a reflux condenser, a
thermometer, and a nitrogen inlet tube. Polymerization was carried
out at 75.degree. C. for 3 hours while performing nitrogen
bubbling, and then 0.5 parts of V-601 was added thereto.
Polymerization was further carried out for 4.5 hours to obtain a
polymer solution containing a polymer (macromonomer M4). When the
obtained polymer solution was sampled, solid content concentration
was measured, and a polymerization conversion rate was calculated
from non-volatile content, the polymerization conversion rate was
100%. Further, in this case, the Mn of the macromonomer M4 was
6,300, the Mw thereof was 10,000, and the PDI thereof was 1.59. The
macromonomer M4 is a macromonomer not having a cycloalkyl
group.
Comparative Synthesis Example 2
Macromonomer M5
[0103] 250 parts of MFTG, 36 parts of MMA, 10 parts of ethyl
methacrylate (hereinafter, referred to as "EMA"), parts of
2-ethylhexyl methacrylate (hereinafter, referred to as "2-EHMA"),
24 parts of MAA, 2.5 parts of EBMA, and 1 part of V-601 were put
into a reaction container provided with a stirrer, a reflux
condenser, a thermometer, and a nitrogen inlet tube. Polymerization
was carried out at 75.degree. C. for 3 hours while performing
nitrogen bubbling, and then 0.5 parts of V-601 was added thereto.
Polymerization was further carried out for 4.5 hours to obtain a
polymer solution containing a polymer (macromonomer M5). When the
obtained polymer solution was sampled, solid content concentration
was measured, and a polymerization conversion rate was calculated
from non-volatile content, the polymerization conversion rate was
100%. Further, in this case, the Mn of the macromonomer M5 was
7,400, the Mw thereof was 11,000, and the PDI thereof was 1.49. The
macromonomer M5 is a macromonomer not having a cycloalkyl
group.
Synthesis of Graft Copolymer
Synthesis Example 3
Graft Copolymer G1
[0104] 300 parts of a solution of the macromonomer M2 was put into
a reaction container A provided with a stirrer, a reflux condenser,
a thermometer, and a nitrogen inlet tube, and heated to 80.degree.
C. Further, 67 parts of St, 33 parts of BA, and 2 parts of PBO were
put into another reaction container, and stirred to prepare a
monomer solution. 1/2 of this monomer solution was put into the
reaction container A, and the residual 1/2 thereof was slowly
dropped over 1 hour. After the completion of the dropping,
polymerization was carried out for 3 hours. 1 part of PBO was added
thereto, and the mixture was heated to 85.degree. C. and further
polymerized for 4 hours. The resulting product was neutralized by
the addition of 16.1 parts of KOH and 183.9 parts of water, so as
to obtain a polymer solution containing a polymer (copolymer G1).
When the obtained polymer solution was sampled, solid content
concentration was measured, and a polymerization conversion rate
was calculated from non-volatile content, the polymerization
conversion rate was 100%. Further, in this case, the Mn of the
copolymer G1 was 11,400, the Mw thereof was 27,500, and the PDI
thereof was 2.41.
Synthesis Example 4
Graft Copolymer G2
[0105] 300 parts of a solution of the macromonomer M2 was put into
a reaction container A provided with a stirrer, a reflux condenser,
a thermometer, and a nitrogen inlet tube, and heated to 80.degree.
C. Further, 67 parts of St, 33 parts of HEMA, and 2 parts of PBO
were put into another reaction container, and stirred to prepare a
monomer solution. 1/2 of this monomer solution was put into the
reaction container A, and the residual 1/2 thereof was slowly
dropped over 1 hour. After the completion of the dropping,
polymerization was carried out for 3 hours. 1 part of PBO was added
thereto, and the mixture was heated to 85.degree. C. and further
polymerized for 4 hours. The resulting product was neutralized by
the addition of 16.1 parts of KOH and 183.9 parts of water, so as
to obtain a polymer solution containing a polymer (copolymer G2).
When the obtained polymer solution was sampled, solid content
concentration was measured, and a polymerization conversion rate
was calculated from non-volatile content, the polymerization
conversion rate was 100%. Further, in this case, the Mn of the
copolymer G2 was 10,600, the Mw thereof was 22,800, and the PDI
thereof was 2.15.
Synthesis Example 5
Graft Copolymer G3
[0106] 50 parts of MFTG and 300 parts of a solution of macromonomer
M3 were put into a reaction container A provided with a stirrer, a
reflux condenser, a thermometer, and a nitrogen inlet tube, and
heated to 80.degree. C. Further, 67 parts of St, 33 parts of HEMA,
and 2 parts of PBO were put into another reaction container, and
stirred to prepare a monomer solution. 1/2 of this monomer solution
was put into the reaction container A, and the residual 1/2 thereof
was slowly dropped over 1 hour. After the completion of the
dropping, polymerization was carried out for 3 hours. 1 part of PBO
was added thereto, and the mixture was heated to 85.degree. C. and
further polymerized for 4 hours. The resulting product was
neutralized by the addition of 16.1 parts of KOH and 183.9 parts of
water, so as to obtain a polymer solution containing a polymer
(copolymer G3). When the obtained polymer solution was sampled,
solid content concentration was measured, and a polymerization
conversion rate was calculated from non-volatile content, the
polymerization conversion rate was 100%. Further, in this case, the
Mn of the copolymer G3 was 9,800, the Mw thereof was 22,200, and
the PDI thereof was 2.27.
Comparative Synthesis Example 3
Graft Copolymer G4
[0107] 50 parts of MFTG and 300 parts of a solution of macromonomer
M4 were put into a reaction container A provided with a stirrer, a
reflux condenser, a thermometer, and a nitrogen inlet tube, and
heated to 80.degree. C. Further, 100 parts of St, 50 parts of BA,
and 2.5 parts of PBO were put into another reaction container, and
stirred to prepare a monomer solution. 1/2 of this monomer solution
was put into the reaction container A, and the residual 1/2 thereof
was slowly dropped over 1 hour. After the completion of the
dropping, polymerization was carried out for 3 hours. 1.25 parts of
PBO was added thereto, and the mixture was heated to 85.degree. C.
and further polymerized for 4 hours. The resulting product was
neutralized by the addition of 16.2 parts of KOH and 233.8 parts of
water, so as to obtain a polymer solution containing a polymer
(copolymer G4). When the obtained polymer solution was sampled,
solid content concentration was measured, and a polymerization
conversion rate was calculated from non-volatile content, the
polymerization conversion rate was 100%. Further, in this case, the
Mn of the copolymer G4 was 14,000, the Mw thereof was 31,700, and
the PDI thereof was 2.26. The copolymer G4 is a graft copolymer not
having a cycloalkyl group in the grafted polymer.
Comparative Synthesis Example 4
Graft Copolymer G5
[0108] 50 parts of MFTG and 300 parts of a solution of macromonomer
M5 were put into a reaction container A provided with a stirrer, a
reflux condenser, a thermometer, and a nitrogen inlet tube, and
heated to 80.degree. C. Further, 100 parts of St, 50 parts of HEMA,
and 2.5 parts of PBO were put into another reaction container, and
stirred to prepare a monomer solution. 1/2 of this monomer solution
was put into the reaction container A, and the residual 1/2 thereof
was slowly dropped over 1 hour. After the completion of the
dropping, polymerization was carried out for 3 hours. 1.25 parts of
PBO was added thereto, and the mixture was heated to 85.degree. C.
and further polymerized for 4 hours. The resulting product was
neutralized by the addition of 16.2 parts of KOH and 233.8 parts of
water, so as to obtain a polymer solution containing a polymer
(copolymer G5). When the obtained polymer solution was sampled,
solid content concentration was measured, and a polymerization
conversion rate was calculated from non-volatile content, the
polymerization conversion rate was 100%. Further, in this case, the
Mn of the copolymer G5 was 15,600, the Mw thereof was 37,000, and
the PDI thereof was 2.37. The copolymer G5 is a graft copolymer not
having a cycloalkyl group in the grafted polymer (polymer chain
A).
Comparative Synthesis Example 5
Graft Copolymer G6
[0109] 50 parts of MFTG and 300 parts of a solution of macromonomer
M2 were put into a reaction container A provided with a stirrer, a
reflux condenser, a thermometer, and a nitrogen inlet tube, and
heated to 80.degree. C. Further, 100 parts of MMA, 50 parts of BA,
and 2.5 parts of PBO were put into another reaction container, and
stirred to prepare a monomer solution. 1/2 of this monomer solution
was put into the reaction container A, and the residual 1/2 thereof
was slowly dropped over 1 hour. After the completion of the
dropping, polymerization was carried out for 3 hours. 1.25 parts of
PBO was added thereto, and the mixture was heated to 85.degree. C.
and further polymerized for 4 hours. The resulting product was
neutralized by the addition of 16.2 parts of KOH and 233.8 parts of
water, so as to obtain a polymer solution containing a polymer
(copolymer G6). When the obtained polymer solution was sampled,
solid content concentration was measured, and a polymerization
conversion rate was calculated from non-volatile content, the
polymerization conversion rate was 85%. Further, in this case, the
Mn of the copolymer G6 was 10,200, the Mw thereof was 23,000, and
the PDI thereof was 2.25. The copolymer G6 is a graft copolymer not
having an aromatic ring or a cycloalkyl group in the main chain
(polymer chain B).
Synthesis Method of Random Copolymer
Comparative Synthesis Example 6
Random Copolymer R1
[0110] 250 parts of MFTG was put into a reaction container A
provided with a stirrer, a reflux condenser, a thermometer, and a
nitrogen inlet tube, and heated to 80.degree. C. Further, 36 parts
of MMA, 40 parts of CHMA, 24 parts of MAA, 100 parts of St, 50
parts of BA, and 7.5 parts of azobisisobutyronitrile (hereinafter,
referred to as "AIBN") were put into another reaction container,
and stirred to prepare a monomer solution. 1/2 of this monomer
solution was put into the reaction container A, and the residual
1/2 thereof was slowly dropped over 1 hour. After the completion of
the dropping, polymerization was carried out for 3 hours. 1.25
parts of AIBN was added thereto, and the mixture was heated to
85.degree. C. and further polymerized for 4 hours. The resulting
product was neutralized by the addition of 16.2 parts of KOH and
233.8 parts of water, so as to obtain a polymer solution containing
a polymer (copolymer R1). When the obtained polymer solution was
sampled, solid content concentration was measured, and a
polymerization conversion rate was calculated from non-volatile
content, the polymerization conversion rate was 100%. Further, in
this case, the Mn of the copolymer R1 was 14,700, the Mw thereof
was 30,600, and the PDI thereof was 2.08. The copolymer R1 is a
random copolymer.
Synthesis of Block Copolymer
Synthesis Example 6
Block Copolymer B1
[0111] 173 parts of MFTG, 1.0 part of iodine, 3.7 parts of
2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile) (hereinafter,
referred to as "V-70"), 42 parts of CHMA, 17.6 parts of benzyl
methacrylate (hereinafter, referred to as "BzMA"), and 0.17 parts
of diphenylmethane (hereinafter, referred to as "DPM") were put
into a reaction container provided with a stirrer, a reflux
condenser, a thermometer, and a nitrogen inlet tube. Polymerization
was carried out at 45.degree. C. for 5.5 hours while performing
nitrogen bubbling to obtain a polymer solution. When the obtained
polymer solution was sampled, solid content concentration was
measured, and a polymerization conversion rate was calculated from
non-volatile content, the polymerization conversion rate was 86%.
The Mn of the polymer contained in the polymer solution was 5,000,
and the PDI thereof was 1.19. Subsequently, the polymer solution
was cooled to 40.degree. C., 16.8 parts of CHMA, 20 parts of MMA,
12.9 parts of MAA, and 1.5 parts of V-70 were added thereto, and
the mixture was polymerized for 3.5 hours. The resulting product
was neutralized by the addition of 8.4 parts of KOH and 49.2 parts
of water, so as to obtain a polymer solution containing a polymer
(block copolymer B1). When the obtained polymer solution was
sampled, solid content concentration was measured, and a
polymerization conversion rate was calculated from non-volatile
content, the polymerization conversion rate was 100%. Further, in
this case, the Mn of the block copolymer B1 was 10,300, and the PDI
thereof was 1.30. Here, based on the results of measuring the solid
content concentration, ion exchange water was added to the obtained
polymer solution to adjust the solid content concentration to 30%.
Even in the following Synthesis Examples, the solid content
concentration was adjusted to 30% in the same manner.
Synthesis Example 7
Block Copolymer B2
[0112] 174 parts of MFTG, 1.0 part of iodine, 3.7 parts of V-70,
29.4 parts of CHMA, 30.8 parts of BzMA, and 0.17 parts of DPM were
put into a reaction container provided with a stirrer, a reflux
condenser, a thermometer, and a nitrogen inlet tube. Polymerization
was carried out at 45.degree. C. for 5.5 hours while performing
nitrogen bubbling to obtain a polymer solution. When the obtained
polymer solution was sampled, solid content concentration was
measured, and a polymerization conversion rate was calculated from
non-volatile content, the polymerization conversion rate was 82%.
Further, in this case, the Mn of the polymer contained in the
polymer solution was 5,700, and the PDI thereof was 1.20.
Subsequently, the polymer solution was cooled to 40.degree. C.,
16.8 parts of CHMA, 20 parts of MMA, 12.9 parts of MAA, and 1.5
parts of V-70 were added thereto, and the mixture was polymerized
for 3.5 hours. The resulting product was neutralized by the
addition of 8.4 parts of KOH and 49.2 parts of water, so as to
obtain a polymer solution containing a polymer (block copolymer
B2). When the obtained polymer solution was sampled, solid content
concentration was measured, and a polymerization conversion rate
was calculated from non-volatile content, the polymerization
conversion rate was 100%. Further, in this case, the Mn of the
block copolymer B2 was 10,300, and the PDI thereof was 1.31.
Synthesis Example 8
Block Copolymer B3
[0113] 168 parts of MFTG, 1.0 part of iodine, 3.7 parts of V-70, 42
parts of CHMA, 13 parts of hydroxyethyl methacrylate (hereinafter,
"HEMA"), and 0.17 parts of DPM were put into a reaction container
provided with a stirrer, a reflux condenser, a thermometer, and a
nitrogen inlet tube. Polymerization was carried out at 45.degree.
C. for 5.5 hours while performing nitrogen bubbling to obtain a
polymer solution. When the obtained polymer solution was sampled,
solid content concentration was measured, and a polymerization
conversion rate was calculated from non-volatile content, the
polymerization conversion rate was 81%. Further, in this case, the
Mn of the polymer contained in the polymer solution was 5,100, and
the PDI thereof was 1.22. Subsequently, the polymer solution was
cooled to 40.degree. C., 16.8 parts of CHMA, 20 parts of MMA, 12.9
parts of MAA, and 1.5 parts of V-70 were added thereto, and the
mixture was polymerized for 3.5 hours. The resulting product was
neutralized by the addition of 8.4 parts of KOH and 47.6 parts of
water, so as to obtain a polymer solution containing a polymer
(block copolymer B3). When the obtained polymer solution was
sampled, solid content concentration was measured, and a
polymerization conversion rate was calculated from non-volatile
content, the polymerization conversion rate was 100%. Further, in
this case, the Mn of the block copolymer B3 was 9,600, and the PDI
thereof was 1.33.
Comparative Synthesis Example 7
Block Copolymer B4
[0114] 128 parts of MFTG, 1.0 part of iodine, 3.7 parts of V-70,
52.2 parts of BzMA, 9.8 parts of HEMA, and 0.17 parts of DPM were
put into a reaction container provided with a stirrer, a reflux
condenser, a thermometer, and a nitrogen inlet tube. Polymerization
was carried out at 45.degree. C. for 5.5 hours while performing
nitrogen bubbling to obtain a polymer solution. When the obtained
polymer solution was sampled, solid content concentration was
measured, and a polymerization conversion rate was calculated from
non-volatile content, the polymerization conversion rate was 80%.
Further, in this case, the Mn of the polymer contained in the
polymer solution was 4,900, and the PDI thereof was 1.26.
Subsequently, the polymer solution was cooled to 40.degree. C.,
20.8 parts of MMA, 40.8 parts of BMA, 15.0 parts of MAA, and 2.3
parts of V-were added thereto, and the mixture was polymerized for
3.5 hours. The resulting product was neutralized by the addition of
9.8 parts of KOH and 32.8 parts of water, so as to obtain a polymer
solution containing a polymer (block copolymer B4). When the
obtained polymer solution was sampled, solid content concentration
was measured, and a polymerization conversion rate was calculated
from non-volatile content, the polymerization conversion rate was
100%. Further, in this case, the Mn of the block copolymer B4 was
9,200, and the PDI thereof was 1.57.
Synthesis Method of Random Copolymer
Comparative Synthesis Example 8
Random Copolymer R2
[0115] 375 parts of MFTG was put into a reaction container A
provided with a stirrer, a reflux condenser, a thermometer, and a
nitrogen inlet tube, and heated to 80.degree. C. Further, 110 parts
of CHMA, 70 parts of BzMA, 40 parts of MMA, 30 parts of MAA, and 12
parts of azobisisobutyronitrile (hereinafter, referred to as
"AIBN") were put into another reaction container, and stirred to
prepare a monomer solution. 1/2 of this monomer solution was put
into the reaction container A, and the residual 1/2 thereof was
slowly dropped over a period of 1 hour. After the completion of the
dropping, polymerization was carried out for 3 hours. 1.5 parts of
AIBN was added thereto, and the mixture was heated to 85.degree. C.
and further polymerized for 4 hours. The resulting product was
neutralized by the addition of 19.6 parts of KOH and 105.4 parts of
water, so as to obtain a polymer solution containing a polymer
(random copolymer R2). When the obtained polymer solution was
sampled, solid content concentration was measured, and a
polymerization conversion rate was calculated from non-volatile
content, the polymerization conversion rate was 100%. Further, in
this case, the Mn of the random copolymer R2 was 12,100, and the
PDI thereof was 2.28.
Preparation Method of Pigment Dispersion
[0116] 233.3 parts of the polymer solution containing the graft
copolymer G1 obtained in the above Synthesis Example, 70 parts of
diethylene glycol monobutyl ether, and 311.7 parts of water were
mixed to obtain a semi-transparent solution having slight
turbidity. 350 parts of azo-based yellow pigment PY-74 (trade name:
"Seika Fast Yellow 2016G", manufactured by Dainichiseika Color
& Chemicals Mfg. Co., Ltd.) was added to the solution, and the
mixture was stirred for 30 minutes using a dispersing machine to
prepare a mill base. Dispersion treatment was carried out at a
peripheral speed of 10 m/s using a horizontal medium dispersing
machine (trade name: "0.6 liter ECM type DYNOMILL", Shinmaru
Enterprises Corporation, zirconia bead diameter: 0.5 mm), so as to
sufficiently disperse pigment in the mill base. Then, 316 parts of
water was added thereto to adjust pigment concentration to 18%. The
mill base taken out from the dispersing machine was centrifugally
separated (7,500 rotations for 20 minutes), and was then filtered
with a 10 .mu.m membrane filter. The resulting product was diluted
with water, so as to obtain an aqueous pigment dispersion for ink
jet (pigment concentration: 14%).
[0117] In addition, a pigment dispersion for a cyan ink composition
and a pigment dispersion for a magenta ink composition were
prepared in the same manner.
Preparation of Ink Composition
[0118] Materials were respectively mixed in the composition ratios
given in Table 1 below, and sufficiently stirred to obtain ink
compositions, respectively. In Table 1 below, the unit of numerical
value is mass %, and the total is 100.0 mass %.
Measurement Method of Absorbance
[0119] The absorbance of each ink composition to light having a
wavelength of 300 nm to 600 nm was measured using Spectrometer
U-3300 manufactured by Hitachi Ltd according to the following
procedures.
Step1: The ink composition of 0.3 g is weighed and put in the
graduated flask of 1 L. Step2: Pure water is added to the graduated
flask of 1 L so that gross weight may become 1 L. Step3: The
absorbance characteristic is measured with the above-mentioned
Spectrometer U-3300.
[0120] From the obtained absorbance chart, the maximum absorption
wavelength and the integrated value of absorbance in each
wavelength band were calculated. FIG. 1 shows charts of absorption
wavelengths of ink compositions (ink) of Examples 3 and 4 and
Comparative Example 4. The charts of FIG. 1 is standardized so that
the maximum value of the measured absorbance chart may become 1.
The absorbance (absorption wavelength characteristics) of yellow
inks of Examples 1, 2, 5, and are also approximately the same as
the absorption wavelength characteristics of yellow inks of
Examples 3 and 4. The absorbance (absorption wavelength
characteristics) of yellow inks of Comparative Examples 1 to 3, 5,
and 6 are also approximately the same as the absorption wavelength
characteristic of yellow ink of Comparative Example 4. Although all
of the inks of Examples 1 to 6 and Comparative Examples 1 to 6 are
yellow inks containing Pigment Yellow 74 as a pigment, absorption
wavelength characteristics of the yellow inks of Examples are
shifted toward long wavelength, compared to in the yellow inks of
Comparative Examples. Therefore, it is considered that the light
resistance of the ink is improved because the deterioration of a
color material is suppressed due to the reduction of absorbance in
the ultraviolet region.
TABLE-US-00001 TABLE 1 Yellow Magenta Cyan composition composition
composition Pigment Yellow 74 5.0 Pigment Red 122 5.0 Pigment Blue
15:3 4.0 Polymer dispersant 2.5 2.5 2.0 (* kinds are described in
Tables 2 and 3) Glycerin 10.0 10.0 10.0 Triethylene glycol 8.0 8.0
8.0 1,2-hexanediol 4.0 4.0 4.0 Triethanolamine 1.0 1.0 1.0 BYK 348
1.0 1.0 1.0 Pure water 68.5 68.5 70.0 100.0 100.0 100.0
TABLE-US-00002 TABLE 2 Comp. Comp. Comp. Comp. Comp. Comp. Ex. 1
Ex. 2 Ex. 3 Ex. 4 Ex. 5 Ex. 6 Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Ex. 6
Composition Pigment PY74 PY74 PY74 PY74 PY74 PY74 PY74 PY74 PY74
PY74 PY74 PY74 Polymer dispersant G1 G2 G3 B1 B2 B3 G4 G5 G6 R1 B4
R2 Absorption Ratio = (300-400 nm)/ 26% 26% 26% 26% 26% 26% 35% 34%
34% 31% 35% 30% characteristics (300-600 nm) Ratio = (500-600 nm)/
7% 6% 7% 5% 5% 5% 4% 4% 4% 4% 4% 4% (300-600 nm) Evaluation Storage
stability 1 1 1 1 1 1 1 1 2 3 1 3 Light resistance 1 1 1 1 1 1 3 3
3 2 3 2
[0121] In Table 2, all of the yellow inks contain Pigment Yellow
74. In the yellow inks of Examples 1 to 6 and Comparative Examples
1 to 6, the kind of polymer dispersant is changed. The absorption
wavelengths of the yellow ink of Example 3 containing polymer
dispersant G3 and the yellow ink of Example 4 containing polymer
dispersant B1 are shifted to a long wavelength region from an
ultraviolet region, as shown in the absorption wavelength
characteristics of FIG. 1. The yellow ink of Example 1 containing
polymer dispersant G1, the yellow ink of Example 2 containing
polymer dispersant G2, the yellow ink of Example 5 containing
polymer dispersant B2, and the yellow ink of Example 6 containing
polymer dispersant B3 also have approximately the same absorption
wavelength characteristics as those of the yellow inks of Examples
3 and 4. In the absorption characteristics of the yellow inks of
Examples 1 to 6, the ratio of (300 nm to 400 nm)/(300 nm to 600 nm)
is 26%. The ratio of (500 nm to 600 nm)/(300 nm to 600 nm) is 5% to
7%. Storage stability is excellent (evaluation 1: good), and light
resistance is excellent (evaluation 1: good). The absorption
wavelength of the yellow ink of Comparative Example 4 containing
polymer dispersant R1 is shifted to an ultraviolet region, as shown
in the absorption wavelength characteristics of FIG. 1. The yellow
ink of Comparative Example 1 containing polymer dispersant G4, the
yellow ink of Comparative Example 2 containing polymer dispersant
G5, the yellow ink of Comparative Example 3 containing polymer
dispersant G6, the yellow ink of Comparative Example 5 containing
polymer dispersant B4, and the yellow ink of Comparative Example
containing polymer dispersant R2 also have approximately the same
absorption wavelength characteristics as those of the yellow ink of
Comparative Example 4. Regarding the absorption characteristics of
the yellow inks of Comparative Examples 1 to 6, the ratio of (300
nm to 400 nm)/(300 nm to 600 nm) is 30% to 35%. The ratio of (500
nm to 600 nm)/(300 nm to 600 nm) is 4%. The storage stability
and/or light resistance are poor (evaluation 2: slightly poor,
evaluation 3: poor).
TABLE-US-00003 TABLE 3 Comp. Comp. Comp. Ex. 7 Ex. 8 Ex. 8 Ex. 9
Ex. 10 Composition Pigment Yellow 74 B1 G3 B1 G5 G5 Pigment Red 122
G5 G5 B1 G5 B1 Pigment Blue 15:3 G5 G5 B1 G5 B1 Evaluation Color
saturation: mixed color 1 2 2 1 2 portion of Cyan and Yellow Color
saturation: mixed color 1 1 3 1 1 portion of Magenta and Yellow
Light resistance 1 1 1 3 3 I.sub.430/I.sub.550 22 15 22 30 30
Storage Stability of Yellow Ink Composition
[0122] After each yellow ink composition was injected into an
aluminum pack and the aluminum pack was sealed, each yellow ink
composition was left for 6 days under an environment of 70.degree.
C. The ink composition before and after the leaving was diluted
with pure water by 3,300 times, and the particle size distribution
of the diluted solution was measured using the Microtrac UPA
(manufactured by Nikkiso Co., Ltd.).
Evaluation Criteria
[0123] 1: The increment of average particle diameter after leaving
is 0 nm or more and less than 30 nm. 2. The increment of average
particle diameter after leaving is 30 nm or more and less than 100
nm. 3. The increment of average particle diameter after leaving is
100 nm or more. (Evaluation 1: good, Evaluation 2: slightly poor,
Evaluation 3: poor)
Color Developing Properties of Ink Set
[0124] The obtained yellow ink, cyan ink, and magenta ink are
combined with each other as described in Table 3 to obtain an ink
set. Subsequently, an ink jet printer (product name: PX-G930,
manufactured by Seiko Epson Corporation) was filled with the each
ink set. Then, it was confirmed that no nozzle is clogged and
normal recording can be performed by filling a head of the printer
with each ink composition. Thereafter, the following gradation
pattern of mixed color was recorded on the EPOSON photo paper at a
recording resolution of 1440.times.720 dpi, so as to obtain a
recorded matter. The operating environment of the printer was
25.degree. C.
Green gradation pattern: a pattern formed such that the ratio of
Cyan and Yellow is 1:1, in which a Duty of 5% to 100% is recorded
at 5% intervals. Red gradation pattern: a pattern formed such that
the ratio of Magenta and Yellow is 1:1, in which a Duty of 5% to
100% is recorded at 5% intervals.
[0125] Here, the "duty" is a value calculated by the following
Equation. In other words, the "duty" may be a printing duty or a
printing rate.
Duty (%)=number of dots actually printed/(vertical
resolution.times.horizontal resolution).times.100
(In the equation, the "number of actually printed dots" is the
number of actually printed dots per unit area, and each of the
"vertical resolution" and "horizontal resolution" is the resolution
per unit area. The "duty 100%" means the maximum weight of
monochromatic ink per unit pixel.
[0126] For each of the obtained recorded matter, the evaluation of
color saturation C* was performed. Specifically, for each of the
obtained recorded matter, the colorimetry of a* value and b* value
was performed using a colorimeter (Gretag Macbeth Spectrolino,
manufactured by X-Rite Inc.) to calculate color saturation C*. The
color saturation C* was evaluated based on the following
criteria.
Evaluation Criteria
Green
[0127] 1: maximum value of C* is 81 or more.
[0128] 2: maximum value of C* is 79 or more and less than 81.
[0129] 3: maximum value of C* is less than 79.
[0130] (Evaluation 1: good, Evaluation 2: slightly poor, Evaluation
3: poor)
Red
[0131] 1: maximum value of C* is 91 or more (vivid).
[0132] 2: maximum value of C* is 89 or more and less than 91
(slightly dull).
[0133] 3: maximum value of C* is less than 89 (dull).
[0134] (Evaluation 1: good, Evaluation 2: slightly poor, Evaluation
3: poor)
Light Resistance of Yellow Ink Composition
[0135] An ink jet printer (product name: PX-G930) was filled with
each of the obtained yellow ink composition. Then, it was confirmed
that no nozzle is clogged and normal recording could be performed
by filling a head of the printer with each yellow ink composition.
A pattern was recorded on the EPOSON photo paper using the yellow
ink composition. The evaluation of light resistance was carried out
under the following test conditions based on JEITA CP3901A.
Thereafter, for each recorded matter, the colorimetry of a* value
and b* value was performed using a colorimeter (Gretag Macbeth
Spectrolino, manufactured by X-Rite Inc.). The light resistance was
evaluated based on the following criteria.
Test Conditions
[0136] Evaluation apparatus: Xenon light resistance tester XL75
(manufactured by Suga Test Instruments Co., Ltd.)
[0137] Temperature in vessel: 23.degree. C.
[0138] BPT: 35.degree. C.
[0139] Humidity: 50% R.H
[0140] Illuminance: 70 klx
Evaluation Criteria
[0141] 1: light resistance is 70 years or more
[0142] 2: light resistance is 50 years to 70 years
[0143] 3: light resistance is 50 years or less
[0144] (Evaluation 1: good, Evaluation 2: slightly poor, Evaluation
3: poor)
[0145] The entire disclosure of Japanese Patent Application No.
2014-174490, filed Aug. 28, 2014 is expressly incorporated by
reference herein.
* * * * *